Battery not charging :: laptop battery memory

21 Feb 2010
Posted by Laptop Junction

Laptop battery memory

Laptop batteries have their own processor / controller managing Lithium Ion cell charging. Parameters of the charging process are stored into memory inside the laptop battery. One of the important memorized parameters over time is remaining laptop battery capacity. The value is a reflection of the remaining life-time capacity of the battery cells.

Laptop battery end of life

Once the remaining laptop battery capacity drops below the minimal capacity threshold, laptop battery charging stops and the laptop battery has reached end of life. This based on the assumption the value of remaining laptop battery capacity is a realistic reflection of the actual state of the battery cells.

With a simple laptop battery test it's possible to get an indication of the remaining laptop battery capacity.
This is the laptop battery life-time capacity (ie: 1 - 2 years) next to the run-time capacity (ie: 2-4 hours)

Below an example of laptop battery memory registers. This is an implementation based on the smart battery specification used in laptop batteries.

An example of the memory registers for a laptop battery with remaining capacity
Example of laptop battery memory registers according to the smart battery specification.
AccPlus V1.0 by MicroSys

Interesting laptop battery memory registers here are:

  1. Design capacity (Top 3rd right column)
  2. Remaining capacity (Bottom 6th in left column, the run-time remaining capacity)
  3. Full charge capacity (in this case the life-time remaining battery capacity)

The values are stored in flash memory and updated by the laptop battery charge controller.

Laptop battery memory reset

Remaining battery capacity is like the ODO meter in a car. Laptop battery manufacturers have implemented anti-tampering measures to avoid laptop battery memory from being reset so charging can continue with depleted laptop battery cells.

As always with anti-tampering measures – there’s a way around with the right knowledge and equipment. A reset of laptop battery memory to factory values can prove whether remaining laptop battery capacity is a realistic reflection of laptop battery life-time.

If so, a reset of laptop battery memory leads to nothing – just an empty laptop battery that needs to be replaced.

Back to the laptop battery charging diagram.